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Landing occurs as U.S. investigators examine another battery involved in a fire

Two Japanese airlines grounded their fleets of the Boeing 787 Dreamliner, which has been beset by a string of mechanical and other problems, after an All Nippon Airways flight made an emergency landing Wednesday.

Japan Airlines has seven of the airplanes and All Nippon Airways normally flies 17.It was not clear how long the JAL and ANA flights would be grounded.

ANA Flight 692, with 129 passengers, made an unscheduled landing at Takamatsu airport in Japan, said airline Vice President Osamu Watanabe, after a battery alarm signal activated on the plane.

Those on board reported a burning smell in the cabin. One alarm indicated smoke in a forward electrical compartment, officials said.

The ANA aircraft left Yamaguchi Ube Airport and was en route to Haneda when the incident occurred, airline spokesman Takuya Taniguchi said.

This battery was involved in a fire aboard a Japan Airlines Boeing 787 January 7 in Boston.

Boeing spokeswoman Lori Gunter said the company is "aware of the event and working with the customer."

Dreamliner troubles dating back four months include reports of an oil leak, a fuel leak, engine cracks and a damaged cockpit window. This follows a very difficult development history that included a series of production setbacks and other delays before the plane entered service in 2011. Fifty of the aircraft have been delivered to airlines.

The National Transportation Safety Board said it was aware of the latest incident in Japan and was gathering information.

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The Federal Aviation Administration, which is responsible for air safety, launched a comprehensive examination on Friday of the Dreamliner's design as well as its manufacture and assembly.

The FAA said it was monitoring the ANA emergency landing report. "The incident will be included in the comprehensive review the FAA began last week of the 787 critical systems, including design, manufacture and assembly," it said in a statement late Tuesday.

The NTSB, meanwhile, continued its investigation of a battery fire last week.

NTSB investigators are disassembling the burned battery involved in the January 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston. This week, the NTSB released photos that showed charred parts and wire bundles.

The fire broke out in the avionics compartment of an empty Dreamliner shortly after it had arrived and passengers had disembarked. A maintenance worker noticed smoke in the belly of the plane and called emergency crews.

The battery powers the auxiliary unit and provides electricity for ground operations. The damaged battery was removed last week and transported to a federal laboratory in Washington, according to the NTSB.

When new, the battery weighs about 63 pounds. It is approximately 19 by 13 by 10 inches. Officials said they made digital radiographs and computer scans to document the internal condition of the battery before taking it apart.

In addition to the NTSB investigation, Japanese and French aviation officials also have launched investigations.

There are more than 150 Dreamliner flights daily, according to Boeing. United Airlines, which has six 787s, debuted the nation's first domestic Dreamliner routes in November with much fanfare.

Ray Conner, the head of Boeing's commercial airplanes unit, said Friday that Boeing is convinced of the aircraft's safety and that the airlines that have bought the plane are also confident in its safety.

"These planes are safe," he said. "We welcome any opportunity to further assure people outside the industry."

One passenger said Friday he would avoid flying on a 787 for the time being.

"I am wary of a plane model that has fire problems and leaks fuel," said Atlanta-based businessman Bobby Burns, a project manager who takes more than 50 trips a year. "I think of it the same as a new car model: Wait a year or two to get all the 'recalls' sorted out."